A semiconductor device includes a pellet into which a semiconductor chip having integrated circuits (ICs) is divided. Such a pellet is mounted on an island of a lead frame. The lead frame has a plurality of leads each having inner and outer leads. The lead frame with the pellet is encapsulated in molding resin except the outer leads.
A conventional lead frame is formed on a metal strip such as plate, sheet, etc. by punching or etching tile metal strip to have predetermined patterns. In general, a plurality of the lead frames are formed simultaneously on one metal strip. The conventional lead frame includes an island on which a pellet is to be mounted, and a plurality of leads are arranged surrounding the island. As explained above, each lead is composed of inner and outer leads which are integral to each other. Each inner lead is extended near the island. On the other hand, tile outer leads are integral with the frame member to be separated therefrom.
The conventional lead frames are soldered on both surface to have a solder layer, and is separated from the frame member by cutting the outer leads at predetermined points.
According to the conventional lead frame, however, there is a disadvantage in that it is difficult to provide stable and reliable connections of a semiconductor device on pads of a printed circuit board, because cross-sectional surfaces of the outer leads which are cut to provide predetermined configuration and length of leads have no solder layer thereon.